The grades on a chemistry midterm at Springer are normally distributed with $\mu = 67$ and $\sigma = 2.0$. William earned a $66$ on the exam. Find the z-score for William's exam grade. Round to two decimal places.
Explanation: A z-score is defined as the number of standard deviations a specific point is away from the mean We can calculate the z-score for William's exam grade by subtracting the mean $(\mu)$ from his grade and then dividing by the standard deviation $(\sigma)$ $ { z = \dfrac{x - {\mu}}{{\sigma}}} $ $ { z = \dfrac{66 - {67}}{{2.0}}} $ ${ z \approx -0.50}$ The z-score is $-0.50$. In other words, William's score was $0.50$ standard deviations below the mean.